Some aspects of the pupil response in relation to stimulus movement and colour

Recent investigations have shown that the activity of the visual system in the processing of some stimulus attributes such as spatial structure and stimulus colour are reflected in the pupil response in the form of a small transient constriction at the stimulus onset. The response amplitude appears to be proportional to the level of activity generated and varies systematically with the properties of the visual stimulus. In this report, it has been shown that the processing of coherent motion information can also produce pupillary changes in the form of pupil motion responses (PMRs). The results show that PMRs are present for both foveal and peripheral stimulus presentations and are not affected significantly by degradation of retinal image quality. It has been demonstrated that PMRs are also elicited to sudden changes in stimulus speed and direction, and that the response amplitudes vary systematically with the percentage change involved. There are extensive psychophysical data showing that blindsight subjects are sensitive to movement information when the stimulus is presented in their blind field. In this study, pupillometric parallels for the psychophysical findings have been demonstrated. Data which reveal the existence of residual chromatic discrimination in the absence of VI have also been obtained in two blindsight subjects. It has been shown that their psychophysical performance improves with the level of chromatic saturation of the stimulus. The pupil colour responses have been investigated under similar conditions. Results show that the pupil responses to coloured stimuli can also be elicited in the blind field and that these responses parallel the psychophysical findings. The results obtained have been discussed in relation to the properties of the neuronal structures and visual pathways which are likely to mediate the observed pupillometric and psychophysical findings

Self-relevance prioritizes access to visual awareness.

As we are cognizant of only a fraction of the available visual inputs at any given time, how is information selected for access to consciousness? In particular, does the personal significance of stimuli influence perceptual selection? Given that self-relevant information is prioritized during various stages of processing, here we hypothesized that self-association may privilege access to awareness under continuous flash suppression (CFS). The results supported this prediction. Compared with geometric shapes referenced to either a friend or stranger, those previously associated with self were prioritized in visual awareness. To establish the basis of this effect, the processes underlying task performance were investigated using a hierarchical drift diffusion model approach. These analyses showed that self-prioritization mapped onto both the decisional (i.e., starting value, z) and nondecisional (i.e., t₀) parameters of the diffusion model. The implications of these findings are considered. (PsycINFO Database Recor

Orienting to threat:Faster localization of fearful facial expressions and body postures revealed by saccadic eye movements

Most studies investigating speeded orientation towards threat have used manual responses. By measuring orienting behaviour using eye movements a more direct and ecologically valid measure of attention can be made. Here, we used a forced-choice saccadic and manual localization task to investigate the speed of discrimination for fearful and neutral body and face images. Fearful/neutral body or face pairs were bilaterally presented for either 20 or 500 ms. Results showed faster saccadic orienting to fearful body and face emotions compared with neutral only at the shortest presentation time (20 ms). For manual responses, faster discrimination of fearful bodies and faces was observed only at the longest duration (500 ms). More errors were made when localizing neutral targets, suggesting that fearful bodies and faces may have captured attention automatically. Results were not attributable to low-level image properties as no threat bias, in terms of reaction time or accuracy, was observed for inverted presentation. Taken together, the results suggest faster localization of threat conveyed both by the face and the body within the oculomotor system. In addition, enhanced detection of fearful body postures suggests that we can readily recognize threat-related information conveyed by body postures in the absence of any face cues

Self-relevance enhances the benefits of attention on perception

Considerable efforts have focused on elucidating the influence that self-relevance exerts on perceptual decision-making. To explore this issue further, the current research explored the extent to which stimulus applicability facilitates the benefits of covert attention on early visual processing. In two experiments, we manipulated the personal-relevance of peripheral cues (i.e., geometric shapes) that preceded the appearance of target stimuli (i.e., Gabors) and asked participants to report the orientation of the stimulus with the highest contrast. The results revealed a significant effect of self-relevance on task performance. First, compared to cues associated with a friend or stranger, self-relevant cues enhanced the apparent contrast of a stimulus. Second, the benefits of self-relevance were most pronounced when cues pertained to identities that were significant (vs. trivial or irrelevant) to observers. Together, these findings demonstrate that self-relevance potentiates the benefits of transient attention on stimulus processing

Does delay impair localisation in blindsight?

Peer reviewedPublisher PD

Inflammatory myofibroblastic tumor of head of pancreas in a 5 Year-Old child

Inflammatory myofibroblastic tumor (IMT) is assumed as a rare benign tumor that can appear in various organs. Since Umiker et al. introduced inflammatory pseudotumors for the first time in 1954, it was found that occurrence in the head of pancreas is very rare (Baião et al., 2019) 1. Differentiating non-neoplastic lesions of pancreas from adenocarcinoma remains a challenge despite advances in diagnostic modalities whereas cystic and solid lesions and some normal anatomic variants can mimic malignancy (Okun and Lewin, 2016 Jan 1) 2. Histologic patterns of IMT can be identified as fibroblastic and myofibroblastic proliferation with inflammatory infiltrate. They are more common in Women and peak of occurrence is between 2 and 16 years of age (Mirshemirani et al., 2011) 3. In head of pancreas the disease can present with obstructive jaundice and the key for diagnosis is having a tissue specimen by means of needle biopsy. Though in all reported cases surgery is suggested as the lone treatment option, its natural history is obscure still and there can be a challenge in its treatment and also the extent of surgery. Here a new case of IMT of head of pancreas is reported. © 202

More or less of me and you: self-relevance augments the effects of item probability on stimulus prioritization

AbstractSelf-relevance exerts a powerful influence on information processing. Compared to material associated with other people, personally meaningful stimuli are prioritized during decision-making. Further exploring the character of this effect, here we considered the extent to which stimulus enhancement is impacted by the frequency of self-relevant versus friend-relevant material. In a matching task, participants reported whether shape-label stimulus pairs corresponded to previously learned associations (e.g., triangle = self, square = friend). Crucially however, before the task commenced, stimulus-based expectancies were provided indicating the probability with which both self- and friend-related shapes would be encountered. The results revealed that task performance was impacted by the frequency of stimulus presentation in combination with the personal relevance of the items. When self- and friend-related shapes appeared with equal frequencies, a self-prioritization effect emerged (Expt. 1). Additionally, in both confirmatory (Expt. 2) and dis-confirmatory (Expt. 3) task contexts, stimuli that were encountered frequently (vs. infrequently) were prioritized, an effect that was most pronounced for self-relevant (vs. friend-relevant) items. Further computational analyses indicated that, in each of the reported experiments, differences in performance were underpinned by variation in the rate of information uptake, with evidence extracted more rapidly from self-relevant compared to friend-relevant stimuli. These findings advance our understanding of the emergence and origin of stimulus-prioritization effects during decisional processing.</jats:p

Self-prioritization and perceptual matching: The effects of temporal construal.

Recent research has revealed that self-referential processing enhances perceptual judgments - the so-called self-prioritization effect. The extent and origin of this effect remains unknown, however. Noting the multifaceted nature of the self, here we hypothesized that temporal influences on self-construal (i.e., past/future-self continuity) may serve as an important determinant of stimulus prioritization. Specifically, as representations of the self increase in abstraction as a function of temporal distance (i.e., distance from now), self-prioritization may only emerge when stimuli are associated with the current self. The results of three experiments supported this prediction. Self-relevance only enhanced performance in a standard perceptual-matching task when stimuli (i.e., geometric shapes) were connected with the current self; representations of the self in the future (Expts. 1 & 2) and past (Expt. 3) failed to facilitate decision making. To identify the processes underlying task performance, data were interrogated using a hierarchical drift diffusion model (HDDM) approach. Results of these analyses revealed that self-prioritization was underpinned by a stimulus bias (i.e., rate of information uptake). Collectively, these findings elucidate when and how self-relevance influences decisional processing

Neuro-cognitive mechanisms of conscious and unconscious visual perception: From a plethora of phenomena to general principles

Psychological and neuroscience approaches have promoted much progress in elucidating the cognitive and neural mechanisms that underlie phenomenal visual awareness during the last decades. In this article, we provide an overview of the latest research investigating important phenomena in conscious and unconscious vision. We identify general principles to characterize conscious and unconscious visual perception, which may serve as important building blocks for a unified model to explain the plethora of findings. We argue that in particular the integration of principles from both conscious and unconscious vision is advantageous and provides critical constraints for developing adequate theoretical models. Based on the principles identified in our review, we outline essential components of a unified model of conscious and unconscious visual perception. We propose that awareness refers to consolidated visual representations, which are accessible to the entire brain and therefore globally available. However, visual awareness not only depends on consolidation within the visual system, but is additionally the result of a post-sensory gating process, which is mediated by higher-level cognitive control mechanisms. We further propose that amplification of visual representations by attentional sensitization is not exclusive to the domain of conscious perception, but also applies to visual stimuli, which remain unconscious. Conscious and unconscious processing modes are highly interdependent with influences in both directions. We therefore argue that exactly this interdependence renders a unified model of conscious and unconscious visual perception valuable. Computational modeling jointly with focused experimental research could lead to a better understanding of the plethora of empirical phenomena in consciousness research